Find the (8)th term of the AP (9,5,1,-3,\ldots).
Answer and explanation
Correct answer: -19
In this AP, the first term is \(a=9\) and the common difference is \(d=5-9=-4\). The \(n\)th term is given by \(a_n=a+(n-1)d\). Therefore, \(a_8=9+(8-1)(-4)=9-28=-19\). Hence, option B is correct. \(-15\) is the seventh term, since \(a_7=9+6(-4)=-15\). Exam tip: use \(n-1\) in the nth-term formula and put a negative common difference in brackets.
Frequently asked questions
What is the correct answer to this question?
-19
Why is this the correct answer?
In this AP, the first term is \(a=9\) and the common difference is \(d=5-9=-4\). The \(n\)th term is given by \(a_n=a+(n-1)d\). Therefore, \(a_8=9+(8-1)(-4)=9-28=-19\). Hence, option B is correct. \(-15\) is the seventh term, since \(a_7=9+6(-4)=-15\). Exam tip: use \(n-1\) in the nth-term formula and put a negative common difference in brackets.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Finding the $n$th term of an AP.
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